Circuit breaker with wafety reset



CIRCUIT BREAKER WITH SAFETY RESET Cleon F. Frey, RR. 2, Sebastian, Fla., and Myron F. Melvin, 1107 Layman Ave., Indianapolis, Ind.

Filed Apr. 16, 1959, Ser. No. 806,821

7 Claims. (Cl. 200116) This invention relates generally to electrical circuit breakers, and in particular to resettable circuit breakers or overload protective switches having means for preventing the bypassing or incapacitating of its safety function during the resetting operation.

In the functioning of resettable overload protective devices, conditions may exist which permit the safety features of the device to be bypassed and cause damage to the device itself. Specifically, with the overload protective switch in use on an electrical appliance, television receiver or the like, the user of the appliance might, by manipulating the reset button, hold the switch contacts closed under overload conditions. In our copending application Serial No. 752,971, filed August 4, 1958, and titled Circuit Breaker Device, now Patent No. 2,910,- 561, there is disclosed and claimed an arrangement wherein the breaker contacts are shunted each time the reset button is actuated. This structure prevents damage to the breaker device itself when the reset button is retained in actuated position during an overload condition, however, it does not prevent the protected appliance or similar device from being subected to the damaging overload.

It is the primary object of the present invention to provide a resettable circuit breaker device in which the overload protective features of the device cannot be bypassed by retaining the reset member in actuated position.

It is a further objet of the present invention to provide a resettable circuit breaker device in which the reset member not only resets a movable contact supporting member to a normal configuration, but also actuates an auxiliary member to hold the supporting member in open-contact position until the reset member is released.

It is a further object of the present invention to provide a circuit breaker device having safety reset features which is of relatively simple construction and which readily lends itself to low-cost, mass production.

It is a further object of the present invention to provide a resettable circuit breaker device in which a unitary component serves to block the breaker contacts open when the reset member is actuated and also functions as a return spring for the reset member.

The full nature of the invention will be understood from the accompanying drawings and the following description and claims:

Fig. 1 is a side sectional view of an apparatus embodying the present invention.

Fig. 2 is a view similar to Fig. 1 showing the apparatus in tripped position.-

Fig. 3 is a view similar to Fig. 1, illustrating the resetting of the apparatus.

The circuit breaker housing and portions of the switch structure are described only generally since they are described in full detail in our above-mentioned copending application. Referring to the drawings, reference numeral 10 indicates a base plate upon which is mounted a housing which includes a top plate 11 and end plates 1'2 and 13. A casing indicated generally at 14 encloses the housing. Extending through the base plate and mounted United States Patent Patented Aug. 9,

thereon is a conductive member having one end 16 formed to provide the stationary contact of the switch structure, the other end 17 of the conductive member extending exteriorly of the housing to provide a terminal lug.

The housing top plate is provided with an aperture 18, one margin of which receives a clip 19. Supported between the lower end of the clip 19 and an appropriately notched and slotted portion of the housing end wall 12 is a tripping element 21. A stud 22, carried by the trip ping element and formed of copper or similar material, provides a thermal reservoir. As may be seen in Fig. 1, the tripping element 21 is supported under deforming compressive stress. All or a portion of the tripping member may be formed of thermally responsive bimetal which, upon an increase of internal temperature, serves to snap the tripping element from its stable position of Fig. 1 to its stable position of Fig. 2. The depending portion of the clip 19 may be also formed of bimetal so that ambient temperature componesation is provided for the tripping element.

Extending from the central portion of the tripping element 21 is an auxiliary blade 23, formed at its free end to provide a movable contact 24 which cooperates with the stationary contact 16. The housing end wall 13 has a tab 13a which extends through an appropriate slot in the base plate 10 and serves as a terminal lug. It may thus be seen that the electrical circuit through the switching device proceeds from the lug 13a through the housing end wall 13, tripping element 21, auxiliary blade 23, movable contact 24, stationary contact 16 to lug 17. Thus, upon a predetermined increase in current carried by the contacts, the tripping element will snap from its stable position of Fig. 1 into its stable position of Fig. 2, thereby opening the contacts 16 and 24.

A resetting means is provided for returning the tripping element to its position of Fig. 1. This resetting means includes a reset pin 26 which is freely received within the aperture in the upper plate of the casing 14. An annular shoulder 27 on the pin prevents its withdrawal from the casing. A reduced portion 28 of the pin extends through an aperture 29 in the top plate 11 with the shoulder 31 limiting the extent of insertion of the pin into the housing. A resilient blade 32 is secured at its upper end by any suitable means to a more rigid member 33 to form a generally V-shaped reset lever. The free end of the member 33 is curved downwardly and extends through the aperture 18 in the plate 11 and is engaged by the lower end of the reset pin 26. The leg of the reset lever formed by the resilient member 32 extends through a cutaway portion of the side wall 13 and the top plate 11 and its lower end is provided with an inwardly extending portion 34 which is adapted to cooperate with the down turned end 23a of the auxiliary blade 23. When assembled with the housing, the legs of the reset lever are stressed so that the resulting restoring force generated in the lever tends to widen its included angle. In its position of Fig. 1, therefore, the reset lever urges the reset pin into its extreme outer position and the resilient leg 32 bears against the inner face of the side wall 13.

In operation, upon the occurrence of an overload current through the contacts 16 and 24, the tripping element will snap to its position of Fig. 2, opening the contacts. As will be evident from Fig. 3, by depressing the reset pin 26, the engagement of the under face of the leg 33 of the tripping elementwill snap it to its stableposition in which the contacts are closed. Inward movement of the reset pin serves to further deform the resilient leg 32 of the reset lever and causes it to move upwardly along the inner face of the end wall 13. Movement of the reset lever to its position of Fig. 3 thus moves the extending end 34- of the resilient leg 32 into position of Fig. 3, the contacts 'will be blocked open,

even though the tripping element has been returned to its lower stable position.

Upon release of the reset pin, the restoring force generated by the deformation of the reset lever will return the pin to its deactuated position of Pig. 1 and will simultaneously move the leg 32 of the reset lever downwardly along the inner face of the end wall 1'3 to thereby release the auxiliary blade 23, permitting contacts 16 and 24 to reclose.

From the foregoing it will be evident that the circuit breaker contacts are held open during the resetting operation and are permitted to close only when the reset pin is released. This arrangement prevents damage to the protected appliance or electronic circuit which might occur if the reset pin were actuated before the conditions causing the current overload were alleviated. The arrangement also prevents a bypassing of the protective features of the circuit breaker by taping or otherwise blocking the reset pin in actuated position. It should further be noted that in the structure of the present invention the unitary reset lever functions both to provide the contact blocking action and to provide a return spring for moving the reset pin back to its deactuated position subsequent to the resetting operation.

While the invention has been disclosed and described in some detail in the drawings and foregoing description, they are to be considered as illustrative and not restrictive in character, as modifications may readily sug gest themselves to persons skilled in this art and within the broad scope of the invention, reference being had to the appended claims.

The invention claimed is:

1. An overload circuit breaker comprising a base plate and an overlying housing, a fixed contact mounted on the base plate, a tripping element pivotally mounted at each of its ends adjacent said fixed contact and including a bimetal blade, said tripping element being under deforming compressive stress and movable between first and second stable positions on opposite sides of its axis of support, an auxiliary blade mounted on said tripping element and extending undirectionally therewith, a movable contact carried by said auxiliary blade and cooperating with said fixed contact, said bimetal blade being adapted to deflect in response to a predetermined current carried by said contacts to move said tripping element from its said first stable position to its said second stable position, a reset member movably supported on said housing and accessible exteriorly thereof, said reset member being adapted when actuated to return said tripping element from its said second position to its said first position, and means for preventing closure of said contacts until said reset member is deactuated, said means including a reset lever movably supported on said housing and having a portion en- 'gageable with the free end of said auxiliary blade and a further portion engageable with said reset member whereby upon actuation of said reset member said lever blocks movement of said auxiliary blade to contactclosing position and upon deactuation of said reset member said lever frees said auxiliary blade for movement to contact-closing position.

2. An overload circuit breaker comprising a base plate and an overlying housing, a fixed contact mounted on the base plate, a tripping element pivotally mounted at each of its ends adjacent said fixed contact, said tripping element being under deforming compressive stress and movable between first and second stable positions on opposite sides of its axis of support, an auxiliary blade -mounted on said tripping element and extending unidirectionally therewith, a movable contact carried by said auxiliary blade and cooperating with said fixed contact,

means for deflecting said tripping element in response to a predetermined current carried by said contacts from its said first stable position to its said second stable position, a reset member movably supported on said housing and accessible exteriorly thereof, said reset member being adapted when actuated to return said tripping element from its said second position to its said first position, and means for preventing closure of said contacts until said reset member is deactuated, said means including a reset lever movably supported on said housing and having a portion engageable with the free end of said auxiliary blade and a further portion engageable with said reset member whereby upon actuation of said reset member said lever blocks movement of said auxiliary blade to contact-closing position and upon deactuation of said reset member said lever frees said auxiliary blade for movement to contact-closing position.

3. An overload circuit breaker comprising a base plate and an overlying housing, a fixed contact mounted on the base plate, a tripping element pivotally mounted at each of its ends adjacent said fixed contact and including a bimetal blade, said tripping element being under deforming compressive stress and movable between first and second stable positions on opposite sides of its axis of support, an auxiliary blade mounted on said tripping element and extending unidirectionally therewith, a movable contact by said auxiliary blade and cooperating with said fixed contact, said bimetal blade being adapted to deflect in response to a predetermined current carried by said contacts to move said tripping element from its said first stable position to its said second stable position, a reset member adapted when actuated to return said tripping element from its said second position to its said first position, and means for preventing closure of said contacts until said reset member is deactuated, said means including a reset lever having a portion engageable with the free end of said auxiliary blade and a further portion engageable with said reset member whereby upon actuating of said reset member said lever blocks movement of said auxiliary blade to contact-closing position and upon deaotuation of said reset member said lever frees said auxiliary blade for movement to contact-closing position.

4. An overload circuit breaker comprising a housing having a base plate and a top plate spaced therefrom, "a fixed contact disposed within said housing, a tripping element within said housing movable between two stable positions, a contact blade cooperating with said fixed contact and movable by said tripping element into and out of engagement with said fixed contact, a reset pin extending through said top plate and supported for movement into and out of said housing, said reset pin being manually movable from a deactuated position to an actuated position to displace said tripping element from one of its stable positions to the other, and unitary means for urging said reset pin from its actuated position to its deactuated position and for blocking said contact blade out of engagement with said fixed contact when said pin is in actuated position, said means comprising an elongated element substantially spanning the distance between said base and top plates, a generally V-shaped reset lever having its legs extending into said housing and stressed so that the restoring force generated in said lever tends to widen its included angle, one of the legs of said lever being engaged by said reset pin and the other slidably engaging said elongated element, an abutment carried by said other leg adapted to block said contact blade out of engagement with said fixed contact while said reset pin is in actuated position, the restoring force generated in said reset lever urging said reset pin toward deactuated position and said abutment out of blocking relation with said contact blade.

5. An overload circuit breaker comprising a housing having a base plate, a contact disposed within said housing, a tripping element within said housing movable between two stable positions, a contact blade cooperating with said contact and movable by said tripping element into and out of engagement with said contact, a reset pin supported for movement into and out of said housing, said reset pin being manually movable from a deactuated position to displace said tripping element from one of its stable positions to the other, and unitary means for urging said reset pin from its actuated position to its deactuated position and for blocking said contact blade out of engagement with said fixed contact when said pin is in actuated position, said means comprising an elongated element substantially extending normal to the plane of said base, a generally V-shaped reset lever having its legs stressed so that the restoring force generated in said lever tends to Widen its included angle, one of the legs of said lever being engaged by said reset pin and the other slidably engaging said elongated element, an abutment carried by said other leg adapted to block said contact blade out of engagement with said contact while said reset pin is in actuated position, the restoring force generated in said reset lever urging said reset pin toward deactuated position and said abutment out of blocking relation with said contact blade.

6. An overload circuit breaker comprising a housing having a base plate and a top plate spaced therefrom, a fixed contact disposed within said housing, a tripping element within said housing movable between two stable positions, a contact blade cooperating with said fixed contact and movable by said tripping element into and out of engagement with said fixed contact, a reset pin extending through said top plate and supported for movement into and out of said housing, said reset pin being manually movable from a deactuated position to an actuated position to displace said tripping element from one of its stable positions to the other, and unitary means for urging said reset pin from its actuated position to its deactuated position and for blocking said contact blade out of engagement with said fixed contact when said pin is in actuated .position, said means comprising an elongated element substantially spanning the distance between said base and top plates, a reset lever having a portion slidably engaging said elongated element, said lever being resiliently deformed by said engagement, an abutment carried by said further portion of said lever adapted to block said contact blade out of engagement with said fixed contact while said reset pin is in actuated position, the restoring force generated in said reset lever urging said reset pin toward deactuated position and said abutment out of blocking relation with said contact blade.

7. An overload circuit breaker comprising a housing having a base plate, a contact disposed within said housing, a tripping element within said housing movable between two stable positions, a contact blade cooperating with said contact and movable by said tripping element into and out of engagement with said contact, a reset pin supported for movement into and out of said housing, said reset pin being manually movable from a deactuated position to an actuated position to displace said tripping element from one of its stable positions to the other, and unitary means for urging said reset pin from its actuated position to its deactuated position and for blocking said contact blade out of engagement with said fixed contact when said pin is in actuated position, said means comprising an elongated element substantially extending normal to the plane of said base, a reset lever having a portion engaged by said reset pin and a further portion slidably engaging said elongated element, said lever being resiliently deformed by said engagement, an abutment carried by .said further portion of said lever adapted to block said contact blade out of engagement with said contact while said reset pin is in actuated position, the restoring force generated in said reset lever urging said reset pin toward deactuated position and said abutment out of blocking relation with said contact base.

References Cited in the file of this patent UNITED STATES PATENTS 2,577,425 Marcoz Dec. 4, 1951 2,701,829 Krieger Feb. 8, 1955 2,745,922 Roberts et al May 15, 1956 

